The problem (as I'm sure you know) is these lines: AudioStreamBasicDescription desc; asbd=[value getValue:desc]; That is not how you call getValue:. There are two things wrong: You need to supply (where you are saying desc) the address of a buffer, not (as you are doing) the name of an uninitialized...

Static classes are considered evil by some people, but that is just an opinion. When I have these questions, I take a look at the .NET-framework: How is it solved inside there? Sometimes a singleton can be refactored to a static class. It depends on the situation. If your singleton...

At the moment I only can imagine that you don't call GameController.sharedInstance.onProblemSolved() when you want to append a String to problemsSolved. You should also consider making your functions and variables in GameController static. If this doesn't solve your problem I would need more information about how and when you add...

What you want to do is to configure validation for your connections. When a connection is borrowed from the pool you want to make sure that that connection is valid. For this you can specify the validationQuery property on your datasource. <bean id="datasourceAR_XXX" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" scope="singleton"> <property name="driverClassName"><value>oracle.jdbc.driver.OracleDriver</value></property> <property...

From what I have understood, you are actually trying to create an Abstract class that will hold the implementations of few common attributes and behaviors of different types of Rooms. Yes, I mentioned it as Abstract instead of Singleton because you want to use Room without instantiating it, but in...

I suggest you to read referencede articles from comments: Lazy Class Implementing the Singleton Pattern in C# In all cases the Lazy<T> class is thread-safe, but you need to remember that the Value of this type can be thread-unsafe, and can be corrupted in multithreading environment: private static Lazy<MyClass> _instance...

The problem is that you defined TheUniverse as Universe::GetInstance();, with a semicolon. Therefore, after macros are processed, you get Universe::GetInstance();.Initialize(); which is obviously not what you want. To fix the problem simply remove the semicolon in the macro definition.

You didn't add the code for mainactivity or guimanager, so it's anyone's guess. However if the references to RingBuffer aren't "automatically" updated, it's probably because you store the reference in a variable, as such: RingBuffer rb = RingBuffer.getInstance(); And then use rb variable. Don't do that if you're going to...

No, since you can't create instances of a static class there will only be one copy of the field, so there is no need to use the Singleton pattern. Place the construction in the static constructor, which is guaranteed to be called only once, and is thereby automatically thread-safe: https://msdn.microsoft.com/en-us/library/k9x6w0hc.aspx...

Does Singleton.Instance.WriteLine("Hello!"); maintain the lock during the execution of the entire method of WriteLine? No, the lock guards only the creation of your singleton. WriteLine executes unlocked (unless, of course, it obtains its own lock internally). Is Console.WriteLine("Hello!") also completely thread safe like Singleton.Instance.WriteLine("Hello!")? It is equally as safe...

1/ Model You have to know that Mage::getSingleton() is going to send you a singleton (which is a common development design pattern). For magento, only Models can be instantiated as a Singleton Snippet from app/Mage.php where you can see that Magento is actually using getModel behind the scene, and also...

At first you should do what tkanzakic wrote to use the singleton. Then you have to check if your dictionary is valid: if var unwrapped_Dic = singletonClass.provisionalDataDict { m_CountryTextField.text = unwrapped_Dic.valueForKey("country") as NSString } if you work with optionals, you always should check if the forced unwrapping was successful. ...

This is a common pattern that has been addressed many times in many environments. The primary issue you need to address is the speed of despatch of the commands that arrive. You must ensure that no command can clog up the system otherwise you will get unpredictable response times. To...

I think you are confused on what one of those entities is, they are not similar in the slightest (apart from being a part of software engineering...). A singleton is a single object (of any class you like) that can be accessed from anywhere in the entire project by any...

A reference is not an address of an object. It is just an alias for one. You simply have to de-reference the pointer: return *_instance; This lets the reference refer to the object pointed at by _instance. Note that the implementation can be greatly simplified: SingletonSample& SingletonSample::Instance() { static SingletonSample...

When you have a temptation to make something a singleton, think this way: Will this class be really one per application forever? (In your cases I can see, for example, that after some time you will want administrator logging in as some user of your application and will you will...

TL;DR: Prolog is right. And you really are doing the best taking the messages seriously. You are using if-then-else in an unconventional manner. For this reason it is not that simple to figure out what is happening. When I say listing(check) I get the following: check(A, B) :- ( related_to(A,...

You're almost there; you just can't use new self() like this because it's trying to do a new A(). Instead, use get_called_class() so that a new B is created instead. // ONLY SUPPORTS ONE SUBCLASS // KEEP READING BELOW FOR COMPLETE SOLUTION abstract class A { static protected $instance =...

After testing (By putting a print statement in the constructor) , I found that - In the above code, the instantiation will not occur untill the call to MySingleton.getInstance() But if you put the static MySingleton object as a direct property of the class, instead of inside the enum ,...

Generating the comparer definitely costs more than storing it. It's a heap allocation, and more than one (you have to allocate the auto-generated class for the lambda). You probably shouldn't worry about it though. The overhead is very small. Your edit is fine. You don't even need to use a...

In viewDidLoad method you are creating a different object by using protocolPlay = [[PlayerManager alloc]init]; line and set the delegate of this object while you have to set the delegate of shared object. Solution is: - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically...

When main code calls Singleton::getInstance()->someMethod() for the first time, isn't the class instantiated twice? No. Calling a static member of Singleton does not instantiate Singleton, so the only instance of Singleton to exist here is the one you create with new. And you only create it once, because once...

You can create a Service Provider for this. First create the provider with this command: php artisan make:provider OAuthServiceProvider The new provider will be generated in app/Providers/OAuthServiceProvider.php. Then register the singleton in the register method of the provider: <?php namespace App\Providers; use Illuminate\Support\ServiceProvider; class OAuthServiceProvider extends ServiceProvider { public function...

It will be collected if there are no dependencies which really will pin your object. There you just have a reference to the Singleton object. If Singleton somehow retains a refence to your Controllers, than yes, your contollers will be hold in memory....

You can simply use a property observer for the variable, labelChange, and call the function that you want to call inside didSet (or willSet if you want to call it before it has been set): class SharingManager { var labelChange: String = Model().callElements() { didSet { updateLable() } } static...

Technically, what you have is not a global variable, it is a singleton. Its name, GlobalVariables, is not very descriptive, though. Since singletons in iOS applications are often used to make a model, good chances are that your GlobalVariables could be renamed to Model. Next, you could minimize the need...

Trying to modify immutable array(NSArray) will lead to this. Replace [responseObject objectForKey:@"timeline"] with [[NSMutableArray alloc] initWithArray:[responseObject objectForKey:@"timeline"] This was based on the comments of the question....

A singleton can not be inner, because there is only one instance of it, and instances of inner classes keep references to instances of outer (enclosing) classes. Therefore, singleton objects can not hold references to enclosing classes, and can not access their properties. As a workaround, use anonymous objects, which...

The differences between a class and an enum are not so big. I changed the first line of code to public enum instead of public class and added the name of your instance. public enum Employee { // changed "class" to enum INSTANCE; // added name of the (single) instance...

The first question asks what this means: private static Singleton singleton = new Singleton(); This could have equally been written as: private static Singleton myVariable = new Singleton(); When you see Class class it's a variable declaration. The first word is the type of the variable, and the second is...

GeoFenceController will use a global resource - the pool of 20 regions available to your app. That pool is implemented in such a way, that not only a capacity is shared among all the instances of CLLocationManager, all the regions will be effectively shared as well, as all instances of...

Found out the fix after browsing the source code: ((scala.tools.nsc.interpreter.IMain) engine).settings().embeddedDefaults(Main.class.getClassLoader()); This changes the ClassLoader for the ScriptEngine to the same one....

IMHO access via Controller.Instance is for the clients of Controller, internally you should use the controller fields and methods directly, you don't need to know whether your class is being used as a singleton or not.

Swift 1.2 makes it really easy to create singletons. The static instance will be initialised only once and dictObject will be available for other classes to retrieve. class SharedManager { static let sharedInstance = SharedManager() var dictObject = // some default value } ...

Turns out the Singleton works, what doesn't is enabling a button to both (1) store to the Singleton and (2) segue to my 2nd interface controller. To get around this I moved Singleton.instance.salesPriceAsInt = salesPrice.toInt()! to the didActivate method...

I figured it out by using @PreDestroy or Publish of the application server. The problem is "normal". With using Eclipse as an IDE after the server start the application will be published again. Therefore you'll only see one log message of @PreDestroy but two of @PostConstruct. The same goes for...

You seem not to understand the concept that this example is trying to explain. ChocolateBoiler is not a real boiler, it's a java class. However, this class could be used to instruct a piece of hardware (a real boiler controller) to execute some actions. If you mistakenly had two instances...

the correct way to save and restore data when the screen goes to the background or rotates is fragments Here they are talking about data that is obtained dynamically, either as input data from the user or data coming from a sensor or web-service. This data needs to be...

There's a distinct difference between the two concepts that you're talking about. A Singleton class means that only one instance of a class exists at any given time. A Ninject Singleton simply means that Ninject will only ever inject a single instance of a class into your application. There's nothing...

The only way I see is to use a lock on the method you are calling to do the database management. public class Dal { private static object syncObject = new object(); public static void InsertUpdate(...) { lock (syncObject) { // 1. Get the document type = "inv" , current...

Kotlin "object" is thread-safe by construction. As you can see in any decompile/dumping tool, declared object is just final class with static instance initialization + language syntax sugar to simplify instance access

No, because services are singletons by design. Quote from the docs: Note: All services in Angular are singletons. That means that the injector uses each recipe at most once to create the object. The injector then caches the reference for all future needs. Source: angular docs...

The instance will remain null until the property is accessed. Depending on how you're inspecting this, your tooling may be causing that discrepancy. That being said, a simpler and nicer "lazy initialized" singleton pattern would be to use Lazy<T> instead: public sealed class HubErrorList { private static Lazy<HubErrorList> instance =...

Instead of store->AddItemToShoppingCart(item); use Store::instance()->AddItemToShoppingCart(item); You don't need to store the pointer to the singleton in main.cpp or any other function that uses the singleton. Access the singleton by calling Store::instance() whenever you need it. In main, you can use: int main() { Store::instance()->GetDepts(); return 0; } and remove the...

Your current approach with the interface is flawed. By default, all methods in an interface (up until Java 8) are static, and are implemented by instance methods in the implementing class. This means, this is not an option. After all, you'll need to run the method to create an instance,...

Answer is their definitions : JavaScript Singleton pattern ensure that only a single instance of the class may exits in application. A plugin is a piece of software that acts as an add-on to a web browser and gives the browser additional functionality. Plugins can allow a web browser to...

From §4.8.1 of the EJB 3.1 specification: In some cases, explicit initialization ordering dependencies exist between multiple Singleton components in an application. The DependsOn annotation is used to express these dependencies. A DependsOn dependency is used in cases where one Singleton must initialize before one or more other Singletons. The...

You just need to register MyClass as a SingleInstance with your container: var builder = new ContainerBuilder(); builder.RegisterType<MyClass>().As<IMyClass>().SingleInstance(); Then inject where ever you need: public AnotherClass(IMyClass myClass) { _myClass = myClass; } Although it's probably the cache you want a single instance of. In that case: builder.RegisterType<MemoryCacheManager>().SingleInstance(); And then: public...

No, the singleton pattern should be avoided in Android. Why? Because the singleton pattern uses a static instance field. Static fields like that should be avoided because the OS can unload your class and you loose all its content. So my suggestion is to remove the singleton pattern or use...

I don't think any issue will highlight if you use it in a single JVM (the class will hold the reference for the static singleton instance, no matter how you serialize it). Perhaps restarting after the serialization and reading the file would help, but I would think that class loading...

You shouldn't use a DB connection as an attribute in a singleton class. It's bad design. By definition, your singleton which is a GUI element shouldn't even be concerned about DB connections at all. What you should do is have a CRUDManager class (for database create/read/update/delete) that can be called...

How do I assign a default value to a static property? If it's an object, like in this case, you can't. With primitives, you can do something like this: <?hh // strict class Foo { private static int $x = 0; // ... } However, for objects, you'd need...

Your build output shows that you somehow managed to force the compiler to actually compile d3d9_object.h file. This is completely unacceptable. You are not supposed to compile header files. Header files are supposed to be included into .cpp files, not compiled by themselves. Because of that problem, your d3d9_object.h, after...

Got it! Ubuntu seems to use the --as-needed linker option by default, where as Fedora may not. Turning it off will add libcase.so library to the needed list for unittest. After deploying the library (or using LD_LIBRARY_PATH) the unittest works now. unittest: libcase.so g++ -o unittest test_main.cpp -Wl,--no-as-needed -L. -lcase...

"1) Should I invoke Interface or Implementation class from the rest of my program whenever I need to use the class? How exactly should I do so?" Use the interface, that will less clutter your code with Implementation::Instance() calls: Interface& module = Implementation::Instance(); // ^ Note the reference, assignment...

I think, eventually, you won't be making a singleton of an UIViewController. What you probably want is to create a class, like Person. Still if you wan't to do it like you did static let sharedViewController = ViewController() isn't the same object as self. import UIKit class ViewController: UIViewController {...

The code below adds a lock into your service to keep other threads from executing the enclosed statements concurrently. public class CAImportService: ICAImportService { // OTHER METHODS AND SECTIONS REMOVED FOR CLARITY // Define static object for the lock public static readonly object _lock = new object(); /// <summary> ///...

Yes. Typically data was stored in static variables. Static variables are not great for a variety of reasons including unit testing. Additionally, static variables require some kind of synchronization, and a strict reading of the EJB spec does not allow that though in practice it worked fine. Typically the...

Well so far I haven't got any concrete answer for my question. Therefore, I decided implement a different solution which is mentioned here. Unfortunately, the original issue hold true in both approach. So i decided to do a workaround on top of the second approach (see the url) to solve...

The static constructor is called when your class is called the very first time, no matter if by a static call like SingleTon.MyMember or by creating a new instance of it. The other one is always called, when you instantiate a new instance (which in case of a singleton however...

The actual enum behavior of instatiating the instance doesn't have an issue with thread safety. However, you will need to make sure that the instance state itself is thread-safe. The interactions with the fields and methods of Application are the risk--using either careful synchronization and locking, or purely concurrent data...

Seems to me like you placed an ad on each view controller. When you transition between view controllers a new ad is called. You should instead use a singular ad banner. That way no matter what view controller you're on there will always be 1 ad banner running across both...

Notice, the reference holding the Singleton instance is a static class member. private static Singleton singleton = new Singleton(); So although, new Singleton() might look like creating a new instance every time, it's not because that static member gets initialized only once when the class is loaded. The getInstance() static...

You made a mistake by dividing an int to an int and expect a double as it's outcome. You need to devide by a double: public static final double GLOBALSCALE = SCREENWIDTH / 1920.0; Notice the difference, 1920.0 is a double while 1920 is an int. If one of the...

First off I need to clear something basic, assume I have a synchronized block or a synchronized method and one thread already entered the synchronized part and 5 new threads try to access the synchronized part, will they stop running until the first thread leaves the synchronized part? and...

The problem derives from the fact that the Derived class inherits like this: DerivedService : Service<DerivedService> if you want the class to succeed you can write it like that: public class DerivedService<T> : Service<T> where T : DerivedService<T>, new { { ... } } ...

In Go, if your package depends on something external you import said thing. So, unless it's impossible for some reason, you should import the package that instantiates bucket and take it from there, either directly assigning it or in your package's init function. import "my/other/pkg" var bucket = pkg.InitBucket() However,...

If you use this method of singletons, to actually access the singleton you need to use DataWarehouse.sharedData, instead of DataWarehouse(), when you are 'constructing' the datawarehouse object within the other classes. At the moment you never actually access sharedInstance. If you are using Swift 1.2 and prefer, you can use...

As of Java 5, that implementation is safe. However, consider using an internal class instead: final class HelperWrapper { private static final class DeferredLoader { public static final Helper HELPER_INSTANCE = new Helper(); } public static Helper getHelper() { return DeferredLoader.HELPER_INSTANCE; } } This both provides thread-safety and lazy initialization...

I would be really surprised if that code (simplified in the example I'm guessing) does what you say. This: var first_function=require(./first_function)(global_var); passes global_var (which isn't global by the way, as it's defined with var) in to the exported function. The exported function returns that value incremented by one. So when...

Yes, a wcf singleton service can have multiple endpoints. The problem was solved by using [ServiceKnownType(typeof(MyService1))] over the method declaration in IMyService interface. Like, [ServiceKnownType(typeof(MyService1))] public void MethodCall(IMyService1 obj); It was a serialization issue....

this (and hence self) simply refers to the global object (i.e. window). That's why you get the error, there is no global add function. I recommend to read the MDN documentation to learn how this works. One solution is to keep a reference to the object you are returning and...

Assuming that the only place where Obj is set is in the static constructor, the first code snippet is correct; the second code snippet is redundant. Since static constructors run only once per class. If there is no other path to set Obj, its value will always be null at...